Garry's Mod vs Starbound
Garry's Mod
Garry's Mod is a sandbox game that brings back the hilarity and joy of being able to simply experiment and have fun. There aren't any objectives in this game; you are simply given the tools you need to play with... just like that time when you get your first Lego set. Being a purely community-driven game, Garry's Mod is quite the multiplayer game. You can hop into any of the created content or game modes and have fun with your friends, except for buy-to-play games in which you'll need to own the base game first. You can also opt to spend time to create new content that you can then share with the community. If you'd rather play in peace, you can play Garry's Mod offline too.Garry's Mod is definitely the sort of game that creative players would enjoy. The amount of stuff you can play there is astounding and of course, you are given absolute freedom to express yourself through your creations if you choose to do so.
Starbound
Starbound is amazingly fun 2D sandbox/exploration game that will put you in the shoes of a spacefarer and a captain of your very own spacecraft. As you travel through space, you will need to stop by planets to collect resources and perhaps even colonize them so you can also gather up a crew to man your ship. There are up to 7 races to play as, a story campaign where you are tasked to save the universe, and 3 different game modes ranging from Casual to Hardcore to either provide you with a fun relaxing experience or to put your survival skills to the test. You can even play the game cooperatively when you want. For modders, you can add in new races, biomes, dungeons, quests and anything else you'd like as well.Starbound can be turned into a pretty much an endless game due to its procedurally generated universe, where you can simply fly around in your spaceship looking for your next big adventure. Thus, you can definitely expect hours of gameplay at the very least for your first playthrough, making this game very well worth its price.